Method of and apparatus for cleaning gases



Nov. 22, 1932.

-A. F. NESBIT METHOD OF AND APPARATUS FOR CLEANING GASES Filed Apri1.27. 1931 3 Sheets-Sheet 2 Il IWI III I II III IIII, II III' I I III III 'IIIIII I III II I I I I I I I l I I I I I I I I l I l I I l 17006270507' 4er/HUE /Vf/T, 5y: y

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Nov. 22', 1932.

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METHOD OF AND APPARATTUS FOR CLEANING GASES Filed April 27.' 1931 s sheets-Sheet s ,4er/HUE /C N555/ T,

Patented Nov. 22, 1932 PATENT OFFICE ARTHUR'F. NESIBIT, 0F WILKINSBUItG, PENNSYLVANIA METHOD 0F AND APPARATUS FOR CLEANING GASES Application led April 27,

This invention relates to a method of and apparatus for separating solid anr1 liquid particles from fluid streams and, while not limited thereto, is particularly adapted for separating solid and liquid particles from gaseous iiuidstreams.

This invention has for its object the provision of a novel form of apparatus for produc* ing flow bodies of electric wind and the provision of a novel method of using said wind to separate the solid and liquid particles from the fluid stream.

1 Another object is to provide a novel arrangement of discharge and grounded electrode units whereby the electrode elements of said discharge electrode unit will serve as baiiies and deflectors and also will be wiped by the fluid stream so as to preionize said stream, and said grounded elect-rode unit will prevent splashing of the particles separated out of the fluid stream.

A further object is to provide means for maintaining the surfaces of the several elements of said grounded electrode unit clean.

Figure 1 is a sectional side elevation of an apparatus constructed in accordance with this invention.

Figure 2 is a sectional elevation taken at right angles to Figure 1.

Figure 3 is an enlarged fragmentary plan showing the mounting for the discharge electrodes. f

Figure 4 is an enlarged cross-sectional view through one of the discharge electrodes.

Figure 5 is an enlarged fragmentary ele-` 1931. seriarivo. 533,310.

for conveying the separated and trapped particles out of the hoppers.

A discharge electrode unit A is suspended from the top of the casing or housing 2 by rods 5 carried by compression insulators 6. 55 The unit A comprises a frame 7 having ver tically disposed horizontally spaced angleiron members 8 along each side and T-shaped center supports 9. The angle-iro'n members 8 are slotted to receive mounting pins 10 car- 60 ried by the outer ends of the electrode elements 12 and the T-shaped center supports carry lugs or pins 13 adapted to be fitted in bearing blocks in the inner ends' of the electrode elements.

While in the structure shown the electrode unit is of such size that the span is too great for a continuous electrode element and, there fore, two electrode elements are shown in line supported at the center by the T-member 9, I do not wish to be limited thereto since in smaller structures one electrode element may span the whole unit A.

The electrode elements 12 are preferably of carrot-shape in cross-section and are formed from sheet metal which is bent upon itself with one edge 15 beveled to form a sharp discharge edge. The relatively fiat sides and rounded upper portions of the elements are such as to suppress corona and cause substantially all the ions to discharge from the sharp edges l5 which, due to the arrangement of the electrode elements, is directed toward the grounded electrode unit B.

The electrode element-s 12 are arranged in 85 vertically spaced horizontal rows with the electrode so arranged that the discharge from the elements of one row is directed between the elements of the next adjacent ro w.

The casing 2 is provided with an inlet conduit 17 for dirty gas and an outlet conduit 18 for clean gas.

The electrode elements 12 are inclined downwardly and in the direction of flow of the gas stream so that they serve as deectors 95 and baflies for the incoming stream of dirty gas, which gas wipes over the elements and thereby becomes preionized suiciently to materially aid in the separation of the solid and liquid partcles therefrom. 1

` and the discharge electrode unit A to prevent the dirty gas rising up around the insulators 6 and depositing foreign matter thereon,

which may cause a breaking down of the insulators. The wall 19 is provided with openings 20 through which rods 5 pass. The openings 20 are surrounded by shields or collars 21 which are connected directly to the grounded wall 19. Discharge collars 22 are mounted on the rods 5 from which ions are vdischarged toward the edges of the shields 21 forming a curtain-like discharge to throw down any dust or other particles tending to flow up through the openings 20.

The grounded electrode unit B comprises a sup rting structure 25 in which is j ournaled a p urality of tubular electrode elements 26 which are provided lwith sprockets 27 connected by a. drive-chain 28 to a motor (not shown) by which the electrode elements may be rotated for cleaning olf any deposits.

. Suitable scraper bars 30 are mounted below each of the grounded electrode elements 26 and are in contact with the electrodes so that when said electrodes are rotated any deposits on their surfaces will be removed.

The scraper bars extend downwardly below the electrode elements 26 for an appreciable distance so as to serve as baiiles and prevent an circula-tion of the gases immediately below e grounded unit B.

In carryin out the method of this invention the disc arge electrode unit A is connectedthroughl one or more of the rods 5 to one side of a high potential electric circuit while the housing 2 and grounded electrode unit B is connected to the ground.

The dirty fluid or gases pass into the casing or housing 2 through the conduit 17 and immediately impinge against and wipe over the discharge electrode elements 12 which are discharging streams of ions toward the grounded electrode elements 26. This wiping action of the dirty fluid over the electrodes preionizes the gas or fluid and aids materially 1n the separation of the solid and liquid particles.

The discharge electrodes 12 produce a field of intense ionization from their edges 15 due to ionic collisions with molecules of the as or fluid. This ionization results in the or-` mation of a large number of small ions. Ions of molecular size and of the same sign of charge as the edges 15 of the electrodes 12 will be repelled from the edges with a velocity of thousands of centimeters er second and in great numbers. These ionic currents thus set up are of sullicient intensity and volume to drag a considerable amount of air and fluid with them so as to form what is known as electric wind which flows from the edges 15 in the form of flow bodies toward the grounded electrode elements 26.

The dirty gases or fluid entering the apparatus through the conduit 17 are forced to flow across the several streams of electric wind produced by the several electrode elements 12, whereby all the dust or other solid or fluid particles are carried out of the stream of fluid by the electric wind and trapped between the grounded electrodes 26.

The electrode elements l2 all produce a unilateral discharge so that the streams of elect-ric wind are all directed toward the grounded electrode elements 26. This forms a curtain of successive streams or sheets of electric wind which insures complete separation of particles from the fluid being cleaned.

Electric wind can only be produced from4 charged electrodes having. points or sharp edges facing a grounded element and in which corona discharge is suppressed. In the region of a point or sharp edge charged to a high potential the electric field will be very 1ntense so as to cause` the small number of ions initially in the fluid to be cleaned to move with sulicient velocity toproduce secondar ionization. Ions having the same sign of c arge as the'point will be rcpelled by it, as heretofore stated, dragging air with them forming electric wind.

The electric wind of this application is not to be confused With corona, which is a luminous discharge from all sides of a conductor or electrode and which depends entirely upon ionization alone for its separating action, since the discharged energy is dissipated from all surfaces rather than concentrated from a single edge or point, and, therefore, the ions are not repelled with sufficient force to drag air with them. While I have disclosed certain specific embodiments of my invention it will be understood that I do not wish to be limited thereto since various modifications may be made without departing from the scope thereof, as delined in the appended claims.

I claim:

1. In an electric precipita-tor for precipitating solid and liquid particles from a stream of fluid flowing therethrough, the combination of a discharge electrode unit and a grounded electrode unit, said discharge electrode unit comprising a plurality of vertically and horizontally spaced dischar e elements, each of said elements having an en arged body portion and a sharp discharge edge directed toward said grounded electrode unit, so as to cause a unilateral discharge of ions from all of said discharge electrode elements toward said grounded electrode unit forming an electric wind.

2. In'an electric precipitator for precipitating solid and liquid particles from a stream of Huid flowing therethrough, the combination of a discharge electrode unit and a grounded electrode unit, said discharge electrode unit comprising a plurality o f vertically and horizontally spaced discharge elements, each of saidelements bein inclined toward said grounded electrode unlt and in the direction of low of the stream of fluid hein acted vupon so as to mechanically deect an baie said fluid stream, said elements each having an enlarged body portion and a sharp dis charge edge directed toward said grounded electrode unit, so as to cause a unilateral discharge of ions from all of said' dischar e electrode elements toward said ground electrode unit forming an electric wind.

' 3. In an electric precipitator for precipitating solid and liquid particles from a stream of Huid flowing therethrough, the combination of a discharge l electrode unit and a grounded electrode unit, said discharge electrode unit comprising a plurality of vertically and horizontally spaced discharge ele-4 ments, each of said elements having an enlarged body portion and a sharpdischarge edge directed toward said grounded electrode unit,` so. as to cause a unilateral discharge of ions from all/of said discharge elecf trode elements toward saidY grounded electrode unit forming an electric wind,and said grounded unit comprising a Vplurality of spaced curved surfaces which permit the separated particles to be blown around and between them.

4. In an electric precipitator for precipitating solid and liquid particles romastream of said stream' of particles, Y r

In testimonywhereof, have hereunto set my hand.

ARTHUR F.,NESBIT. ,o

fluid,- nd trapping said of fluid flowing therethrough, the combina# tion of a discharge electrode unit and a. grounded .electrode unit, said discharge electrode unit comprising a plurality of vertically and horizontally spaced discharge `elements, .each of said elements having an enlarged body portion'and a sharp discharge edge directed toward said grounded elec-y trode unit, so as to cause a unilateral discharge of ions from all of said discharge `lelectrode elements toward said grounded electrode vunit forming an electric wind, said grounded unit comprising. a plurality of spaced rotary cylindrical members which permit the separated particles to beblown be' tween them, and scraper bars arranged on the side of said cylindrical members opposite said discharge electrode elements and adapted to scrape any deposited particles from said cylindrical members, said scraper bars being of considerable width so as to serve as baiiles. 

